1. Field of the Invention
This invention relates generally to multiple beam antennas, and more particularly to a feed horn array for a multiple beam antenna having an overall peripheral aperture shape which is designed to conform to the shape of the desired coverage area of the antenna.
2. Description of the Prior Art
Multiple beam antennas utilizing an array of feed horns are known in the prior art. U.S. Pat. No. 3,633,208, issued Jan. 4, 1972 to James S. Ajioka, describes a shaped-beam antenna for earth coverage from a stabilized satellite. This device utilizes an array of circular horns which produce a desired beam shape. U.S. Pat. No. 4,757,324, issued Jul. 12, 1988 to Sutinder S. Dhanjal, describes an antenna array having hexagonal horns. The '324 patent points out a coverage deficiency in devices that utilize circular feed horn shapes and teaches that an increase in gain can be achieved by eliminating the gaps between the feed horns that are inherent in devices such as Ajioka that utilize circular horns. The utilization of variously shaped horns is also taught in U.S. Pat. Nos. 2,851,686; 3,045,238; 3,482,251; and 3,495,262.
A deficiency in the above-described prior art is that the peripheral shape of the aperture of the antenna feed horn array is not optimized in relation to the shape of the coverage area to which the antenna is to be directed. Optimization of the peripheral shape of the feed horn array aperture to conform to the desired coverage area results in improved gain.